Electro thermostatic appliance



Dec. 20, 1955 u z 2,727,960

ELECTRO THERMOSTATIC APPLIANCE Filed Aug. 13, 1953 INVENTOR 7' H 6? 1 u12 ATTORNEYS United States Patent O ELECTRO THERMOSTATIC APPLIANCEHonorato Gutirrez Ruiz, Mexico City, Mexico Application August 13, 1953,Serial No. 374,082

4 Claims. (Cl. 200-122) This invention relates to electro-thermostaticappliances.

It is well known that in electric circuits fuses are interposed in thecircuits so as to prevent overloading of the circuits or to break thecircuit in the event of an overload. While the fuses accomplish thepurpose for which they were designed, when a fuse blows out areplacement of the fuse is necessary.

It is an object of this invention to provide an improved circuitbreaking means which will eifectively break the circuit when an overloador short circuit occurs, and when the overload or short circuit iseliminated the circuit will be re-established.

Another object of this invention is to provide an improved circuitbreaking means which can be finely adjusted to produce the resultsdesired.

A further object of this invention is to provide an improved circuitbreaking means which will avoid fire hazards due to overloading or shortcircuits.

A further object of this invention is to provide a circuit breakingmeans embodying a glass receptacle filled with inert gas within which athermostatic switch is positioned. The switch is normally closed and oneor more filaments are connected with the switch terminals, and thefilaments are of such capacity and resistance as to be normallyinactive. When an overload occurs the filaments heat up the interior ofthe receptacle and the switch, which is of the thermostatic type, movesto a circuit breaking position.

With the above and other objects in view, my invention consists in thearrangement, combination and details of construction disclosed in thedrawings and specification, and then more particularly pointed out inthe appended claims.

In the drawings:

Figure 1 is a detailed side elevation partly broken away of athermostatic appliance constructed according to an embodiment of thisinvention.

Figure 2 is a diagrammatic view of the appliance interposed in anelectric circuit.

Figure 3 is a detailed side elevation partly broken away of a modifiedform of this invention.

Figure 4 is a diagrammatic view of an electric circuit within which theappliance shown in Figure 3 is interposed.

Referring to the drawing, the numeral designates generally a glass bulbhaving a threaded plug 11 at one end thereof with a center contact 13.The bulb 10 is adapted to be evacuated of air and to then be filled withan inert gas such as nitrogen, argon or the like.

A thermostatic switch generally indicated at 12 is mounted within thebulb 10 and is formed of a pair of bimetallic bars 14 and 15. Bar 14 issecured to a central support 16 and is electrically connected with thethreaded plug 11 as will be hereinafter described. Bar is fixed relativeto bar 14 being secured in spaced parallel relation thereto by means ofan insulated spacer 17. The upper end of bimetallic bar 14 has a contactpoint 18 secured thereto and bimetallic bar 15 has threaded into theupper end thereof a screw 19 carrying contact 20 confronting contact 18and normally disposed in contacting relation with respect to contact 18.A tungsten wire 21 is disposed within the bulb 10 being connected at oneend to bimetallic bar 15, and the other end thereof is connected to anupstanding relatively rigid wire or bar 22 which extends downwardlythrough the lower end of the bulb 10 and is electrically connected withplug 11.

A second tungsten wire 23 is disposed within the bulb 10 and isconnected at one end to bimetallic bar 14. The other end of tungstenwire 23 is connected to a relatively rigid wire or bar 24 disposedwithin the bulb 10 and extending downwardly through the lower end ofbulb 10 and connected with the center contact 13. The thermo staticappliance hereinbefore described is adapted to be connected in series inan electric circuit embodying a pair of conductors 25 and 26. Theappliance hereinbefore described is connected with either one of theconductors 25 or 26 and it will be understood that various electricalappliances such as indicated at 27 are connected between the conductors25 and 26.

Referring now to Figures 3 and 4, there is disclosed a modified form ofthis invention wherein the glass bulb 28 is formed with a metal plug 29and a center contact 30. A pair of bimetallic bars 31 and 32 aredisposed within the bulb 28 which is filled with inert gas. Bar 31 issecured to a central supporting member 33 and bar 32 is fixed adjacentthe lower end thereof relative to bar 31 and is electrically insulatedtherefrom by means of an insulating spacer 34. A tungsten wire 35 isdisposed within the bulb 28 and is connected at one end to bar 31. Theother end of tungsten wire 35 is connected to an upstanding wire orsupport 36 which extends downwardly through the bottom of bulb 28 and isconnected with threaded plug 29. A second tungsten wire 37 is disposedWithin the bulb 28 being connected at one end to the lower end ofbimetallic bar 32 and the other end of tungsten wire 37 is connected toan upstanding relatively rigid bar 38. Bar 38 extends downwardly throughthe bottom of bulb 28 and is connected with center contact 30. The upperend of bar 31 has fixed thereto a contact member 39 and the upper end ofbar 32 has threaded therethrough a screw 40 carrying contact 41 which isnormally engaged with contact 39.

The bridging tungsten wire 42 is connected between the lower ends of thebimetallic bars 31 and 32 and is of such capacity as to reduce theamount of current which may be consumed in the event there is a short oran overload in the electric circuit with which this device is connected.The appliance shown in Figure 3 is adapted to be interposed in one of apair of conductors 43 or 44. The conductors 43 and 44 have connectedthereto one or more electrical appliances 45.

In the use and operation of this thermostatic switch element the bulb 10is adapted to be threaded into a socket which is connected with one sideof an electric circuit and in series in the circuit. At the time theunit is manufactured the screw 19 is adjusted so that contact will benormally maintained between contacts 18 and 20 until a predeterminedoverload or short circuit develops in the electric circuit.

When the overload or short circuit occurs, tungsten wires 21 and 23 willbe abnormally heated, it being understood that the normal loadconditions will keep the tungsten wires 21 and 23 in a relatively coolcondition. When tungsten wires 21 and 23 become unduly heated,bimetallic bars 14 and 15 will flex so as to separate contacts 18 and 20and thereby break the electric circuit to the appliance 27. As soon asthe circuit is broken, the tungsten wires 21 and 23 will cool off andbimetallic members 14 and 15 will again assume the normal position withcontacts 18 and 20 in contacting relation. This action will produce aninterrupted flow of current to appliance 27.

In view of the quick action of the circuit breaking means hereinabovedescribed, in the event there is a short ciredit in the electriccircuit, the circuit will be intermitently' broken in such a manner asto prevent a fire occurring or further damage resulting from the shortcircuit. As soon as the overload has been relieved or the short circuitcorrected, the bimetallic members 14 and 15 will assume their normalcircuit closing position.

The device shown in Figures 3 and 4 will operate in a manner similar tothat shown in Figures 1 and 2 with the exception that tungsten element42 is of relatively heavy capacity and is sufiicient to withstand anoverload or short circuit of the electric circuit. Tungsten member .42,upon overload of the electric circuit will become heated with tungstenmembers 35 and 37 so that the contacts 39 and 41 will be separated andwill be held in separated position as long as tungsten element 42 isalso heated. When the short circuit occurs between conductors 43 and 44tungsten element 42 will absorb sufiicient electric current so that theamount of current passing through tungsten element 42 to the point ofoverload or short circuit will be insuflicient to cause a fire.

The devices hereinbefore described are designed for the purpose oftaking the place of fuses and will provide a means whereby an electriccircuit will be maintained in normally closed position but will bebroken as soon as an overload or short circuit occurs. This device isparticularly useful in locations where it is desired to limit theconsumption of electric current so that only a predetermined amount ofelectric current will normally pass to an appliance which is connectedacross the conductors of the electric circuit.

What is claimed is:

v 1. A thermostatic circuit making and breaking switch comprising a baseformed of non-conducting material, an elongated bi-metallic bar havingone end thereof fixedly secured to said base, a non-conducting spacermember disposed intermediate said first oi-metallic bar and one end of asecond bi-metallic bar, means securing said spacer member and said oneend of said second lat-metallic bar to said first bi-metallic baradjacent its said one end, a switch point mounted on said firstbimetallic bar adjacent the other end thereof, a second switch pointmounted on said second bi-metallic bar, said second switch pointconfronting said first switch point and normally engaging thereagainstin circuit making position, means for adjusting said second switch pointrelative to the first switch point, an electrical resistance elementpositioned proximate to each of said bi-metallic bars in heat exchangerelationship, each of said elements having an end thereof electricallyconnected with their respective proximate bi-metallic oars, and meansfor connecting the other ends of said elements in a load carryingelectric circuit whereby overloading of said circuit draws such currentas to heat abnormally said elements which transfer said heat to theirrespective proximate bars causing the latter to flex thereby separatingsaid switch points and breaking said circuit.

2. A thermostatic circuit as defined in claim 1, and

a third resistance element disposed proximate said bimetallic bars andshunt connected thereacross, said third resistance having a higherresistance than the resistance of said first and second elements.

3. A thermostatic circuit making and breaking switch comprising a baseformed of a dielectric material, a bimetallic bar having one of its endsmounted on said base, a second dielectric bar having one end thereofmounted on said first bar, dielectric spacing means disposedintermediate said first and second bars, a switch point contact mountedon each of said bars adjacent their respective other ends, said switchpoints confronting each other, and normally engaging each other incircuit making position, means for adjusting one of said points relativeto the other, a resistance element positioned adjacent each of said barsin heat exchange relation, said elements having one of their endselectrically connected to their respective adjacent bars, and meansconnecting said other ends of said elements in series in an electriccircuit carrying a load.

4. A thermostatic circuit making and breaking switch as defined in claim3, and a third resistance element disposed proximate said bars in heatexchange relation and shunt connected thereacross.

References Cited in the file of this patent UNITED STATES PATENTS2,543,707 Prouty Feb. 27, 1951 2,615,146 Macksoud Oct. 21, 19522,635,156 Welter Apr. 14, 1953 2,636,077 Jacobson Apr. 21, 19532,658,975 Zuckerman Nov. 10, 1953 FOREIGN PATENTS 784,913 France May 6,1935

